One or two doses of quadrivalent meningococcal serogroups A, C, W-135 and Y tetanus toxoid conjugate vaccine is immunogenic in 9- to 12-month-old children.

Background: The incidence of invasive meningococcal disease is highest in infants. A quadrivalent meningococcal serogroups A, C, W-135 and Y tetanus toxoid conjugate vaccine (MenACWY-TT) was evaluated in children 9-12 months of age.

Methods: We randomized infants (1:1) to receive 1 dose of MenACWY-TT at 12 months of age (ACWY-1 group) or 2 doses at 9 and 12 months (ACWY-2).